1. Field of the Invention
The present invention relates to saw machine technology, and more particularly to a saw machine worktable positioning mechanism used in a saw machine (e.g., miter saw) and operable to lock the worktable of the saw machine.
2. Description of the Related Art
A conventional saw machine (see the description of the related art in Taiwan Patent I466743) generally comprises a base unit, a worktable rotatably supported on the base unit, a saw-cutting unit connected to one side of the worktable, and a positioning unit. The base unit comprises a base and two foot members respectively fastened to two opposite lateral sides of the base. The positioning unit comprises a locking screw threaded into the worktable. When adjusting the cutting angle of the saw-cutting unit, the operator unfastens the locking screw from the worktable, and then rotates the worktable by shifting the saw-cutting unit to the desired cutting angle, and then fastens tightly the locking screw again.
The aforesaid positioning unit can be unfastened for allowing adjustment of the angular position of the saw-cutting unit relative to the base, and then fastened tightly to lock the worktable to the base after adjustment of the angular position of the saw-cutting unit. However, in applying the adjustment, the operator cannot visually check the positioning status of the positioning unit. Further, when rotating the worktable to move the saw-cutting unit relative to the base unit, the lock screw can be forced to rub against the periphery of the worktable, which scratches the periphery of the worktable, e.g., damages the outer surface. Further, the lock screw locks the worktable of the base unit at one single point. If a user fastens the lock screw too tightly, the base can be deformed. If the lock screw is too loose, the worktable will not be locked firmly, resulting in poor positioning.
In order to solve the aforesaid problem, the inventor of the present invention invented Taiwan Patent I466743, which comprises a pivot shaft, a first hold down member, a second clamp, and a linkage unit. Operating an operating member of the linkage unit can bias the linkage unit, forcing a second clamping portion of the second clamp to release the base unit for adjustment of the angular position of the worktable, or to clamp the base unit to lock the worktable.
Further, Taiwan Patent I453080, was also invented by the applicant of the present invention, which teaches the use of a driving device set to hold down an engaging device set and to move a tightening up member in an eccentric manner. Operating the driving device set can simultaneously move the engaging device set and the tightening up member toward or away from the base of the saw machine to lock or unlock the worktable.